MERTIL for Parents: Pilot Study of an Attachment and Trauma-Informed Online Parenting Program

<b>Background:</b> Early relational health is critical for childhood development, and disruptions in infant-caregiver trust can heighten risk. MERTIL <i>for Parents</i> is a brief, universal, online program designed to build parental understanding of relational trust and its role in infant development. This pilot study is the first evaluation of the program. <b>Objectives:</b> To evaluate the acceptability and short-term outcomes of MERTIL <i>for Parents</i>. <b>Methods:</b> Seventy-three parents (<i>n</i> = 69 mothers) of children aged 0-5 years, referred by practitioners, completed the program and online questionnaires at baseline (<i>N</i> = 73), post-intervention (<i>n</i> = 50), and three-month follow-up (<i>n</i> = 25). <b>Results:</b> The program demonstrated high acceptability: 98% of parents who engaged with the program found the content useful, 92% felt the length was appropriate, and all would recommend it to others. Program completion and satisfaction did not vary by sociodemographic or psychosocial characteristics. At three-month follow-up, parents reported significant improvements in their enjoyment of the parent-child relationship (<i>p</i> < 0.001), attunement to their child (<i>p</i> < 0.001), parenting confidence/competence (<i>p</i> = 0.004 and <i>p</i> = 0.003), help-seeking amenability (<i>p</i> < 0.001), and a reduction in irritability toward the child (<i>p</i> < 0.001), with medium to large effect sizes. No significant changes were observed for items assessing reflective functioning or perceived rejection. <b>Conclusions:</b> MERTIL <i>for Parents</i> shows strong acceptability and promising preliminary outcomes as a scalable, attachment and trauma-informed intervention supporting early relational health. Future research should examine long-term impacts and evaluate broader implementation across diverse families and service contexts.